Problem with extrusion

[DGA]

Why the parts of cylinder 2, 3 and 4 are correct but not the 1

see file attached

[Dimitri Harvalias]

Not sure what makes the '1' incorrect. What is the profile supposed to look like?

[DGA]

see this render image

the cylinder 1 dont look like a cylinder
If you see the profile, it is a part of a circle.

(forgive my English)

[Scott Hopkins]

see this render image

the cylinder 1 dont look like a cylinder
If you see the profile, it is a part of a circle.

(forgive my English)
I think what you are running into is a display bug in Revit. Very small cylindrical objects in Revit sometimes display as if they are turned inside out in shaded views. The geometric construction is correct but Revit's shading engine, for what ever reason, can't handle extremely tight curves. If you render the offending objects they will come out looking correct. I hope they fix this problem.

[DGA]

I do not think that it is an error of display under 3dmax the geometrical error is visible.

but i think is a bug

[Scott Hopkins]

You're right! I never tested this problem by translating it to another program. Good catch! That is a much more serious bug than I thought! Revit Factory are you listening?

[sbrown]

Very strange, i think you need to send this one in.

[DGA]

in fact, Revit cannot make a cylinder lower than 1" of diameter.
damage for furniture

[sbrown]

I just did a test , the top is 2", mid 1", lower 1/2" and it does make it, however just as your example shows, something weird happens in the middle. Sections are fine, just the 3d object gets messed up.